1. Field of the Invention
This invention relates to air cylinders utilized to control the performance of various functions, and particularly to an air cylinder piston excursion control apparatus that enables pre-programmed precise stoppage of an air cylinder piston in either direction.
2. Description of the Prior Art
A preliminary patentability search in connection with the subject invention has revealed the existence of the following U.S. Pat. Nos.
______________________________________ 4,554,661 4,043,709 4,199,344 4,686,870 4,736,675 ______________________________________
Referring to the patents listed above in the order of their issuance, it is noted that U.S. Pat. No. 1,544,661 relates to a pump structure for dispensing liquids such as oil or grease, and embodies a rack and pinion arrangement for translation of the piston within a cylinder when a hand-crank is rotated. The piston rod is slidably arranged in a tubular extension, and a push-pin is adjustable in its height within the tubular extension to limit elevation of the piston rod and thereby control the amount of liquid dispensed by the pump.
U.S. Pat. No. 4,043,709 relates conceptually to a method and means of controlling an air cylinder so as to control the amount of liquid dispensed in a pumping operation. Structurally, there is provided a threaded extension rod one end of which functions as a stop. The threaded extension rod is minutely adjustable by rotation to set the stop point of the piston.
U.S. Pat. No. 4,199,344 discloses a structure operated by air that is used in the glass container industry to repeatedly shift a bottle from a cooling station to a moving conveyor. The mechanism for effecting reciprocable action is essentially a rack and pinion arrangement for rotating a shaft on which are fixed two spur gears. A pin on one of the spur gears and a bolt constituting a stop on one of the racks limits the excursion of the rack.
U.S. Pat. No. 4,686,870 discloses a double-acting air cylinder that is mounted for slidable reciprocation on a fixed piston rod and piston assembly. From one end of the reciprocable cylinder there is an extension that extends radially away from the cylinder and moves with the cylinder. Mounted laterally from the cylinder on the same framework is a turret shaft on which are locked a multiplicity of stop rods that may be adjusted incrementally and which may be rotated on the turret shaft so that the ends of the rods are abutted by the lateral extension from the cylinder. Rotation of the turret rod is effected by a pawl and ratchet mechanism.
U.S. Pat. No. 4,736,675 relates to an air cylinder in which the piston is actuated by the admission of air to the cylinder, with means attached to he piston rod to prevent the piston from rotating within the cylinder. There does not appear to be anything in this patent that suggests control of the excursion of the piston in relation to the cylinder.
There are many instances in industry in which it is expedient to use an air cylinder having a piston and piston rod and responsive to the admission of air into the cylinder to displace the piston and cause translation of the piston rod to achieve performance of a given function, say, for example the positioning of a machine part for the performance on that machine part of a grinding or cutting operation, or the assembly on it of some additional part. The use of air and air cylinders to effect such operations is frequently less complex and therefore less expensive than the use of other mechanisms, such as hydraulic, mechanical or electrical means. Accordingly, it is one of the primary objects of the present invention to provide an air cylinder and control apparatus therefor that adapts the air cylinder for use in robotic systems.
In robotic systems, it is frequently necessary that multiple and repetitive functions be performed with exactitude of position of the part being operated upon. Accordingly, another object of the present invention is the provision of an air cylinder and air cylinder control apparatus that enables exact interruption of the translation of the air cylinder piston and the rod to which it is attached at predetermined positions along its excursion path.
The prior art indicated above teaches the broad concept or idea of intermediate stoppage of an air cylinder by mechanical means. However, the prior art so far as known to me does not teach the concept of a structure for providing exact intermediate stops for the piston and piston rod of an air cylinder while traveling in both directions. Accordingly, another object of the invention is the provision of an air cylinder control apparatus that accurately provides predetermined intermediate stops for an air cylinder piston in both directions of its travel.
For effective application in a robotic system, where multiple and repetitive functions must be performed, it is an advantage if the predetermined positional limitations of the apparatus may be preprogrammed into the apparatus. Accordingly, a still further object of the invention is the provision of an air cylinder and air cylinder control apparatus that is susceptible of computer control in its operation.
The invention possesses other objects and features of advantage, some of which, with the foregoing will be apparent from the following description and the drawings. It is to be understood however that the invention is not limited to the embodiment illustrated and described since it may be embodied in various forms within the scope of the appended claims.